Study On The Preparation And Wastewater Purification Of Al₂O₃ Ceramic Membranes

Aluminum material have the advantages of high mechanical strength, high hardness, heat resistance, chemical resistance, inexpensive and readily available; The ceramic membrane prepared by phase inversion have the advantages of short process cycle, ideal asymmetric crosssectional structure and high flux, the combination of both methods can reduce the cost of highperformance ceramic membrane and great practical value.In this paper, α-Al₂O₃ as the inorganic body, under different conditions, a series of alumina plate ceramic membranes were prepared by phase inversion method combined with hightemperature sintering process, and these membranes were characterized by means of FE-SEM, XRD, TG, mechanical properties, porosity, water flux. The results showed that the α-Al₂O₃ crystal form had not changed before and after sintering; Polymer concentration was too low or too high would make the film surface appears agglomerated, The membrane surface separation layer more uniform by the moderate polymer concentration, polymer concentration PES:NMP=1:5, the ceramic membrane surface uniform morphology,flexural strength was 20.3Mpa, porosity of 54.8%, were the best value; With the alumina content increasing, increased the degree of the membrane densification, the membrane surface had better morphology when the alumina content between 45% and 50%, membrane surface morphology, flexural strength, pore size, porosity, water flux parameters were more prominent; With the alumina particle size decreasing, the specific surface area increasing, so that the molten alumina particles more firmly bound to grow, the mechanical strength of the ceramic film increased, the pore size decreased; Ultimately determined the optimum preparation conditions: PES:NMP=1:5, the alumina content of 45%, the alumina particle size at 0.05μm, the prepared alumina plate ceramic membrane separation layer size at about 0.3μm, the flexural strength was 27.6Mpa, the porosity was 48.3%, the water flux was 5200L?h-1?m-2?bar-1.The 0.3μm alumina plate ceramic membranes were applied filtration experiments in restaurant wastewater, Measured the filtering effect through steady flux, oil and COD rejection rates. The results showed that with the feed concentration increasing, the membrane steady flux declined, and the filtering time to reach the steady flux was also reduced, when the feed concentration of 866mg/L, the steady flux, oil and COD rejection rates were more prominent; With the feed liquid flow rate increasing, the steady flux first increased after the film was reduced, change the oil and COD rejection rates were not optimal, feed liquid flow rate was 200L/h; With the operating pressure increasing, the steady flux gradually increased, while the oil and COD rejection rates showed a decreasing trend after the first increased, the optimal operating pressure was 0.16 Mpa, too low or too high operating pressure would cause the oil and COD rejection rates decreased; With the feed temperature increasing, the membrane steady flux decreased after the first increased, the oil and COD rejection rates decreased, ultimately determined the feed temperature was 25℃; The prepared ceramic membranes had stable and high performance of regeneration more than 95%. Ultimately determined the optimal filter conditions: the feed temperature was 25℃, the feed flow rate was 200L/h, the operating pressure was 0.16 Mpa, the feed solution as raw material liquid, then the water flux was 1161L?h-1?m-2, oil and COD rejection rates were 94.61%, 89.24%.